Cetoniacytones A and B are two new microbial secondary metabolites isolated by Zeeck and co-workers from an endosymbiotic Actinomyces sp. strain Lu 9419. This microorganism was isolated from the intestines of an insect Cetonia aureata. The cetoniacytones consist of a unique C7N aminocyclitol unit having an epoxide at C-5, C-6 and in contrast to most of the secondary metabolites belonging to this family, which commonly entail a N-ether linkage at the C-1 position, the nitrogen in the cetoniacytones is located at C-2. Their chemical structures were elucidated by detailed spectroscopic analysis, and the absolute configuration of the major component, cetoniacytone A, was determined by X-ray analysis as well as through derivatization with chiral acids. Despite their unusual chemical structures, the core units of the cetoniacytones appear to be derived via the pentose phosphate pathway as has also been shown for acarbose, the validamycins and the pyralomicins.
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